Compositions for diabetes treatment and prophylaxis

ABSTRACT

Gurmarin containing compositions are useful for modulation of glucose metabolism and the treatment of diabetes. Glucose metabolism in a human patient is regulated by isolated gurmarin-containing dosage forms that contain optionally a non-metabolizable polysaccharide such as the exudate of  Sterculia urens.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of U.S. patent application Ser. No.10/638,811, filed on Aug. 11, 2003, now U.S. Pat. No. 7,115,284.

FIELD OF THE INVENTION

This invention relates to the regulation of glucose metabolism in ahuman patient.

BACKGROUND OF THE INVENTION

The concentration of glucose in the human bloodstream must be controlledwithin a relatively tight range (60-120 milligrams per deciliter ofblood) to maintain normal health. If blood glucose drops too low, acondition known as hypoglycemia results, with symptoms such asfaintness, weakness, headache, confusion and personality changes. Severehypoglycemia can progress to convulsions, coma and death. Excessiveblood glucose, or hyperglycemia, causes excess urine production, thirst,weight loss, fatigue, and in the most severe cases, dehydration, comaand death. Chronic hyperglycemia causes tissue damage due to thechemical reactions between the excess glucose and proteins in cells,tissues, and organs. This damage is thought to cause the diabeticcomplications of blindness, kidney failure, impotence, atherosclerosis,and increased vulnerability to infection.

The pancreas makes hormones that regulate the concentration of glucosein the blood. Insulin lowers blood glucose levels; when glucose levelrises after a meal, the pancreas secretes insulin, which causes muscleand other tissues to take up glucose from the blood stream. Glucagonraises blood glucose levels; when blood glucose levels fall, thepancreas secretes glucagon to signal the liver to make stored glucoseavailable.

A third glucose-regulating hormone, amylin, was discovered in 1987.Physiologists now generally consider that all three hormones play a rolein the complex aspects of glucose metabolism. The chemical structure ofamylin and its metabolic action on muscle and pancreas tissue hasrecently been elucidated. Amylin is said to work with insulin tomoderate the glucose-lowering effects of insulin under certaincircumstances, to help replenish liver glycogen after a meal, and toencourage the synthesis of fat from excess glucose. As a result, amylin,like glucagon, can raise the blood glucose level.

Diabetes mellitus is associated with continuous and pathologicallyelevated blood glucose concentration; it is one of the leading causes ofdeath in the United States and is responsible for about 5% of allmortality. Diabetes is divided into two major sub-classes: Type I, alsoknown as juvenile diabetes, or Insulin-Dependent Diabetes Mellitus(IDDM), and Type II, also known as adult onset diabetes, orNon-Insulin-Dependent Diabetes Mellitus (NIDDM).

According to the American Diabetes Association, there are over onemillion juvenile diabetics in the United States. Diabetes is a form ofautoimmune disease. Autoantibodies produced by the patients completelyor partially destroy the insulin producing cells of the pancreas.Juvenile diabetics must, therefore, receive exogenous insulin duringtheir lifetime. Without treatment, excessive acidosis, dehydration,kidney damage, and death may result. Even with treatment, complicationssuch as blindness, atherosclerosis, and impotence can occur.

There are more than five million Type II (adult onset) diabeticsdiagnosed in the United States. Type II disease usually begins duringmiddle age; the exact cause is unknown. In Type II diabetics, risingblood glucose levels after meals do not properly stimulate insulinproduction by the pancreas. Additionally, peripheral tissues aregenerally resistant to the effects of insulin. The resulting high bloodglucose levels (hyperglycemia) can cause extensive tissue damage. TypeII diabetics are often referred to as insulin resistant. They often havehigher than normal plasma insulin levels (hyperinsulinomia) as the bodyattempts to overcome its insulin resistance. Some researchers nowbelieve that hyperinsulinomia may be a causative factor in thedevelopment of high blood pressure, high levels of circulating lowdensity lipo-proteins (LDLs), and lower than normal levels of thebeneficial high density lipo-proteins (HDLs). While moderate insulinresistance can be compensated for in the early stages of Type IIdiabetes by increased insulin secretion, in advanced disease statesinsulin secretion is also impaired. Treatments of Type II diabetespreferably address both insulin resistance and faulty insulin secretion.

Insulin resistance and hyperinsulinomia have also been linked with twoother metabolic disorders that pose considerable health risks: impairedglucose tolerance and metabolic obesity. Impaired glucose tolerance ischaracterized by normal glucose levels before eating, with a tendencytoward elevated levels (hyperglycemia) following a meal. According tothe World Health Organization, approximately 11% of the U.S. populationbetween the ages of 20 and 74 are estimated to have impaired glucosetolerance. These individuals are considered to be at higher risk fordiabetes and coronary artery disease.

Obesity may also be associated with insulin resistance. A causal linkageamong obesity, impaired glucose tolerance, and Type II diabetes has beenproposed, but a physiological basis has not yet been established. Someresearchers believe that impaired glucose tolerance and diabetes areclinically observed and diagnosed only later in the disease processafter a person has developed insulin resistance and hyperinsulinomia.

Insulin resistance is frequently associated with hypertension, coronaryartery disease (arteriosclerosis), and lactic acidosis, as well asrelated disease states. The fundamental relationship between thesedisease states, and a method of treatment, has not been established.

Insulin and sulfonylureas (oral hypoglycemia therapeutic agents) are thetwo major classes of diabetes medicines prescribed today in the UnitedStates. Insulin is prescribed for both Type I and Type II diabetes,while sulfonylureas are usually prescribed for Type II diabetics only.Sulfonylureas stimulate natural insulin secretion and reduce insulinresistance; these compounds do not replace the function of insulin inmetabolism. Approximately one-third of patients who receive sulfonylureabecome resistant to it. Some Type II diabetics do not respond tosulonylurea therapy. Of patients who do respond to initial treatmentwith sulfonylureas, 5-10% are likely to experience a loss ofsulfonylurea effectiveness after about ten years.

Insulin itself has a relatively narrow therapeutic window. Relativelyhigh insulin doses can produce hypoglycemic shock as the blood glucosedrops too low. Low or infrequent doses may result in hyperglycemia.

In Europe, two other classes of oral hypoglycemic agents are available,i.e., biguanides and alpha-glucosidase inhibitors. Biguanides work byreducing glucose production in the liver and limiting glucoseabsorption. Although biguanides are also used in Canada, they are bannedin the U.S. due to increased incidence of mortality. Alpha-glucosidaseinhibitors are sold in certain European countries, but have not obtainedFDA approval for use in the U.S. These drugs reduce high blood glucoselevels by slowing the uptake of ingested foods. Side effects includeflatulence, diarrhea, and abdominal pain.

U.S. Pat. No. 4,761,286 to Hiji discloses that an aqueous extractderived from the leaves of Gymnema sylvestre can be utilized incombination with a foodstuff that is absorbed as glucose by theintestinal tract so as to inhibit glucose absorption. Chatterji,International Patent Application No. WO 95/10292, reported that glucosemetabolism in a human patient can be effectively modulated by oraladministration of an extract derived from the leaves of G. sylvestre incombination with a bio-inert polysaccharide, i.e., a polysaccharide thatis non-metabolizable by the patient. Heretofore the inhibitory action onthe absorption of sugar in the intestinal tract by G. Sylvestre extractshas been attributed to gymnemic acid and the varius derivatives thereofpresent. See, for example, U.S. Pat. No. 5,137,921 to Kensho et al. andShimizu et al., J. Vet. Med. Sci. 59(4):245-251 (1997).

It has now been found, however, that glucose metabolism in a humanpatient can be effectively modulated by oral administration of gurmarin,a polypeptide; optionally in combination with a non-metabolizablepolysaccharide.

SUMMARY OF THE INVENTION

This invention is directed to compositions and methods for modulatingglucose metabolism in a mammal, such as a human patient.

In one aspect, the present invention provides a relatively highmolecular weight (HMW), gurmarin-containing isolate that can be derivedfrom the leaves of a herb belonging to the plant family Asclepiadaceae,genus Gymnema, that contains gurmarin, a 35 amino acid residuepolypeptide. The present invention also includes therapeutic dosageforms containing gurmarin and pharmaceutically acceptable carriertherefor. Gurmarin can be administered alone or together with anon-metabolizable polysaccharide, preferably a Sterculia urens exudate,preferably in a respective weight ratio in the range of about 1:50 toabout 1:5, more preferably about 1:25.

The aforementioned isolate containing gurmarin is readily obtainable byaqueous or aqueous ethanolic extraction of the leaves of the speciesGymnema sylvestre, followed by isolation of a relatively high molecularweight insulinotropically active principle from the extract. Theisolated, insulinotropically active principle contains gurmarin, havinga molecular size of about 4000 Daltons.

Another aspect of the present invention is a method for modulatingglucose metabolism in a mammal, e.g. a human patient, a household pet,and the like, by orally administering to the mammal an effective amountof isolated gurmarin or of the aforesaid combination of ingredientswhich is sufficient to at least stabilize, and preferably reduce, theblood glucose level of the mammal such as a human patient.

The present compositions are useful as a dietary supplement, to delaythe onset of diabetes, as an adjunct therapy with insulin for Type Idiabetic patients to assist in blood sugar level control, and to reducethe likelihood of the onset of diabetes in those who are geneticallypredisposed to diabetes, cholesterolemia or obesity. The isolate of thepresent invention is also useful for the treatment of diabeticretinopathy.

DESCRIPTION OF PREFERRED EMBODIMENTS

Gurmarin is a 35 amino acid residue polypeptide that includes threeintramolecular disulfide bonds and has a molecular weight of about 4000Daltons. Gurmarin can be obtained by chemical synthesis, and also byextraction from the leaves of a plant from the genus Gymnema (familyAsclepiadaceae) such as G. sylvestre, G. inodorum, and the like. Thestructure of gurmarin (SEO ID NO: 1) can be represented by the formula

wherein the amino terminus is to the left and the three disulfide bondsthat are present are denoted by C₁-C₄, C₂-C₅, and C₃-C₆, respectively.Stated in another way, the disulfide bonds are present between thecysteine residues at positions 3 and 18; 10 and 23; and 17 and 33. Inthe foregoing formula the standard one-letter amino acid residueabbreviations have been used as shown in the following table.

Three-letter One-letter Amino acid abbreviation abbreviation alanine AlaA arginine Arg R asparagine Asn N aspartic acid Asp D cysteine Cys Cglutamic acid Glu E glutamine Gln Q glycine Gly G histidine His Hisoleucine Ile I leucine Leu L lysine Lys K methionine Met Mphenylalanine Phe F proline Pro P serine Ser S threonine Thr Ttryptophan Trp W tyrosine Tyr Y valine Val VGurmarin has been reported as suppressing the response of the rat chordatympani nerve to sweet taste stimuli such as glucose, sucrose, glycineand saccharine, but as having no apparent effect in humans. Fletcher etal., Eur. J. Biochem. 264:525-533 (1999). It has now been found,however, that gurmarin has insulinotropic properties and is useful formodulation of glucose metabolism in human patents alone, or inconjunction with a non-metabolizable polysaccharide such as Sterculiaurens.

A convenient source of gurmarin is Gymnema sylvestre, a plant thatbelongs to the family Asclepiadaceae. The plant grows principally inCentral and Western India, in tropical Africa and in Australia. It hasbeen reported that the raw leaves of G. sylvestre have been used inIndia as a folk medicine for various afflictions including diabetesmellitus. Some fourteen or fifteen different compounds, all having arelatively lower molecular weight, are reported to have been isolatedfrom the leaves of G. sylvestre by various techniques (see, e.g.,Stocklin, J. Agr. Food Chem., 1969, 17(4):704-708 and Sinsheimer, J.Pharm. Sci., 1970, 59(5):622-628). U.S. Pat. No. 5,137,921 reports thatConduritol A, a low molecular weight monosaccharide (M.W. 146) isolatedfrom plants such as Marsdenia condurango and Gymnema sylvestre, is anactive anti-diabetic agent.

Another possible source of gurmarin is G. inodorum leaf extract. G.inodorum is liana plant that grows wild in Southwest Asia. Other Gymnemaspecies are G. lignosum, G. pachyglossum, G. stenophyllum.

Gurmarin can be obtained from a water extract or an aqueous alcoholicextract of fresh G. sylvestre leaves by size selective filtration of theextract to isolate selected molecular weight, insulinotropically activefractions therefrom. In one preferred embodiment, the obtained isolatehaving a molecular weight of at least about 3000 Daltons, as determinedby molecular weight cut-off (MWCO) filtration, contains gurmarin and isillustrative of a gurmarin isolate suitable for practicing the presentinvention.

Preferably an extract is obtained by extraction of G. sylvestre leaveswith a monohydric C1 to C4 alcohol, e.g., ethanol, isopropanol, and thelike, most preferably aqueous ethanol. The insulinotropically activeportion of the G. sylvestre extract is then isolated by molecular weightcut-off filtration. In particular, the active portion is isolated byfiltration of an aqueous solution of the extract through a membranehaving a molecular weight cut-off of about 3000 Daltons, and thematerial retained by the membrane (i.e., the retentate), which has amolecular weight of at least about 3000 Daltons, is collected andisolated.

The gurmarin containing product of the present invention is preferablyprepared by soaking fresh leaves of G. sylvestre for at least about 4hours at ambient temperature in an aqueous alcoholic solution,preferably an aqueous ethanolic solution containing about 40 volumepercent of ethanol. If water is used as the sole extraction medium, thetemperature is somewhat higher, e.g., about 35 to about 85° C.

In a preferred embodiment, the leaves are soaked in water for about 4 to24 hours, preferably about 18 hours, and then ethanol is added to thewater to obtain an ethanol concentration of at least about 40% byvolume, and the soaking is continued in the resulting aqueous ethanolsolution for at least about 4 hours thereafter. The resulting liquidextract is filtered to remove extraneous solids and distilled to driveoff ethanol and produce an aqueous bottoms solution, which is thentreated with sulfuric acid to lower the pH thereof to a value of no morethan about 2 and to precipitate out acid-insoluble salts that had beenproduced. The precipitates are removed by filtration, and the filtrateis neutralized with sodium hydroxide. The neutralized extract is thenconcentrated, and purified to produce a gurmarin containing isolate (the“isolate”).

This isolate is then preferably lyophilized to enhance storage life andcombined with a pharmaceutically acceptable carrier for oraladministration. Optionally, the isolate is combined with anon-metabolizable polysaccharide such as Sterculia urens exudate, or ahydroxypropylmethylcellulose (HPMC), to produce an oral dosage form thatcontains gurmarin. As used herein and in the appended claims, the term“non-metabolizable polysaccharide” refers to a polysaccharide that isnot significantly metabolized by a human patient. Also suitable for thepresent purposes as a non-metabolizable polysaccharide are the partiallyesterified oligosaccharides and polysaccharides disclosed in U.S. Pat.No. 4,959,466 to White. Illustrative are polysaccharides include, forexample, xanthan gum, guar gum, gum arabic, the alginates, hydroxypropylcellulose, cellulose hydrolysis products, starch hydrolysis products,karaya gum, and the like. Preferably, the non-metabolizablepolysaccharide is the dried exudate of the tree S. urens, found inIndia, and readily available commercially.

In a preferred embodiment, the gurmarin-containing isolate is preferablylyophilized and combined with the non-metabolizable polysaccharide in aweight ratio in the range of about 2:1 to about 1:2, respectively, toprovide a gurmarin-to-polysaccharide weight ratio in the range of about1:50 to about 1:5, more preferably about 1:25. The resulting combinationcan then be filled into hard gelatin capsules for oral administrationwith or without excipients. A typical gelatin capsule embodying thepresent invention contains about 100 to about 200 milligrams of thelyophilized gurmarin-containing isolate and about 150 to about 300milligrams of S. urens exudate.

The dosage and therapeutically effective amount to be administered to ahuman patient for modulating glucose metabolism of the patient will varydepending upon, inter alia, the age, weight and condition of thepatient. The usual daily dosage is preferably in the range of about 200milligrams to about 900 milligrams of the gurmarin-containinglyophilized isolate per day, preferably in conjunction with about 300milligrams to about 1350 milligrams of non-metabolizable polysaccharidesuch as S. urens exudate.

As used herein, the term “therapeutically effective amount” means thatamount of the isolate that will elicit the biological or medicalresponse of a patient that is being sought by a clinician.

The term “pharmaceutically acceptable carrier” as used herein means anon-toxic, inert solid, semi-solid or liquid filler, diluent,encapsulating material or formulation auxiliary of any type.

A preferred schedule of administration using capsules containing about100 milligrams of the lyophilized isolate and about 150 milligrams S.urens exudate is provided in Table 1, below.

TABLE 1 Dosage Schedules Patient diagnosis Dosage Schedule*Hyperinsulinemia 1-2 capsules b.i.d. Type II diabetic (moderate) 2capsules b.i.d. Type II diabetic (high) 2-3 capsules t.i.d. Type Idiabetic (moderate) 1 capsule b.i.d. Type I diabetic (high) with insulin2 capsules t.i.d. as adjunct therapy *b.i.d. = 2 times per day; t.i.d. =3 times per day

The present oral dosage forms are eminently well suited as prophylacticsfor patients genetically pre-disposed toward diabetes, cholesterolemiaor obesity.

The dosage regimen for the present, gurmarin-containing compositions isbased on a variety of factors, including the type, age, weight, sex andmedical condition of the patient, the severity of condition, and thelike.

For example, expectant mothers identified as likely to be sopre-disposed on the basis of family history, can take oral doses of theaforedescribed lyophilized isolate throughout the full terms of theirrespective pregnancies. The likelihood of elevated blood sugar levelsfor the mothers and their newborn babies is greatly minimized in thismanner. For expectant mothers, the preferred oral dosage is about 200milligrams of the lyophilized isolate together with about 300 milligramsof S. urens exudate twice daily, i.e., a 500 milligram capsule, b.i.d.,containing the lyophilized isolate of the present invention and the S.urens exudate in a respective weight ratio of about 2:3. The isolate ofthe present invention is also useful for the treatment of diabeticretinopathy.

The gurmarin containing isolate of the present invention can beevaluated for insulinotropic activity by a variety of procedures, wellknown in the art. For example, insulin producing cells can be treatedwith the isolate of the present invention and the insulin production ofthe cells can be monitored by the double antibody method of Morgan etal., Diabetes 12:115-126 (1963), the relevant disclosure of which isincorporated herein by reference. Rat insulinoma (RIN) cells are aconvenient model for studying effects of pharmaceutical agents, such asthe isolate of the present invention, on mammalian insulin production.RIN cells can be cultured in a glucose rich medium such as Dulbecco'sModified Eagle's Medium (D-MEM), which contains glucose (typically about0.1 to about 0.5% by weight) and about 10% by weight of fetal calf serum(FCS), and which provides nutrients such as glucose, amino acids, andvitamins suitable for mammalian cell metabolism.

The present invention is further illustrated by the followingnon-limiting examples.

EXAMPLE 1 Preparation of Extract and Isolate

Fresh leaves of Gymnema sylvestre were purchased and identified by abotanist. The fresh leaves were soaked for about 18 hours in tap water(about 1 kg leaves/4 L tap water) at ambient temperature. Aqueous ethylalcohol (about 90 volume percent ethanol) was added thereto insufficient quantity to bring the net alcohol percent level to about 40%by volume, and the entire batch was distributed with stirring into tenErlenmeyer flasks. Flasks were placed on a shaker table and shaken forabout four hours.

The flask contents were filtered and the recovered liquid extract wasdistilled in several batches to remove ethyl alcohol. The obtainedaqueous bottoms solutions were combined, and dilute sulfuric acid (about1 to 2 molar) was added thereto to reach a final pH of about 2. A sludgecomposed of acid-insoluble salts was formed and was removed byfiltration. Soluble salts of sodium and potassium, inherent from theleaves, remained in the filtrate. The filtrate was neutralized withdilute sodium hydroxide and deionized by passing through an ion exchangecolumn. The resulting solution (eluate) was concentrated to a semi-solidlight-brown mass (a “syrupy” mass the consistency of molasses) using arotary flask equipped with a vacuum, with the rotary flask rotated at a45 degree angle on a water bath heated to a temperature of about 55-70°C.

The semi-solid concentrate was then subjected to ultrafiltration usingstirred Amicon filtration cells and molecular weight cut-off (MWCO)membranes. In particular, the obtained semi-solid concentrate wasfractionated using 200 mL Amicon stirred ultrafiltration cells(Millipore Catalog No. 5123) and matching 3000 MWCO membranes (MilliporeCatalog No. PLBC 06210) to obtain a permeate fraction having a molecularweight less than about 3000 Daltons and a retentate fraction (theisolate) having a molecular weight of at least about 3000 Daltons.

EXAMPLE 2 Bioassay of Gymnema sylvestre Isolate

The insulin-releasing activity of the obtained permeate and retentate ofExample 1 were tested by radioimmunoassay (RIA) using an RIA kit(Catalog No. RI-13K) purchased from Linco Research, Inc., St. Louis,Mo., utilizing rat insulinoma (RIN-58) cells, I-125 labeled insulin, ratinsulin antiserum, and the double antibody technique of Morgan et al.,Diabetes 12:115-126 (1963). The main activity was found in theretentate, which has a MWCO of at least about 3000 Daltons.

Rat insulinoma cells (RIN-58) were plated in 6-well plates and grown ina tissue culture medium that contained glucose. At 80% confluence, themedium was replaced with a glucose-free medium. About 24 hours later,fresh serum-free medium containing 10 mM glucose was added along withthe fraction to be assayed. The cells were incubated for 3 hours.Duplicate aliquots of 25 μl each were drawn from the wells for RIA. Theassay results are reported in Table 2, below.

TABLE 2 Bioassay of Insulin-Releasing Activity Fraction ActivityRetentate (MW ≧3000 Daltons)  9.5 ng/mL Permeate (MW <3000 Daltons) 2.35ng/mL

EXAMPLE 3 Assay for Gurmarin

A lyophilized isolate of Example 1 was dissolved in TRIS-buffered water(Tris/Tris HCl; pH about 8.2) and placed in about 1 milliliter ofCoomassie® Reagent solution contained in a 10-milliliter vial. Thesample exhibited a color change from brown to blue at 4° C. This colorchange indicates the presence of a polypeptide or protein.

The development of color in Coomassie® dye-based protein and polypeptideassays is believed to be associated with the presence of certain basicamino acid residues (primarily arginine (R), lysine (K) and histidine(H)). In general, the mass of a protein or peptide must be at least3,000 Daltons to be assayed in this manner.

EXAMPLE 4 Elemental Analysis

A lyophilized isolate of Example 1 was analyzed for the presence ofsulfur, carbon, hydrogen, and nitrogen. The analytical results are setforth below:

sulfur 0.14 wt.-% carbon 21.67 wt.-%  hydrogen 5.37 wt.-% nitrogen 6.19wt.-%

EXAMPLE 5 Quantitative Assay for Polypeptide

A lyophilized isolate of Example 1 was dissolved in TRIS-buffered water(Tris/Tris HCl) and subjected to the Coomassie® Protein assay using aCoomassie® Protein Assay Kit 23200 (Pierce, Rockford, Ill.) and bovineserum albumin (BSA) as the standard protein against which to measure theconcentration. The standards were made using aqueous 40% ethanol as thediluent. The Coomassie® Reagent was equilibrated at room temperature forall samples and standards.

Each standard (0.1 ml) of an established concentration was placed in a20-milliliter vial and Coomassie® Reagent (5 ml) was added thereto. Eachsample was prepared in a similar manner. The vials were then incubatedfor 10 minutes at room temperature.

Measurements were made on a Varian Cary 5000 double beam UV-Vis-NIRspectrophotometer. Each sample was stirred before being placed in apolystyrene cuvette. The blank for determining the UV-Vis baseline wasaqueous 40% ethanol.

An absorbance value at 595 nanometers was determined, and a plot of thenoted absorbance value @ 595 nm vs. BSA concentration in μg/ml(concentration curve) was prepared. Any obvious outliers were removedfrom the plot and a best fit linear regression was applied. Theresulting line equation Y=MX+B and R² linearity values (Y=Absorbance @595 nm; X=concentration in μg/ml) were found to be Y═0.001X+0.5174,R²=0.9974. The polypeptide concentration was determined from the plotand back calculated from the concentration curve to determine the amountof polypeptide present. The experimental results are presented below:

Amount of Sample Calculated wt.-% Polypeptide 0.01231 g/2 ml 3.3

These experimental results confirm the presence of a sulfur-containingpolypeptide in the lyophilized isolate, i.e., the retentate fractionhaving a molecular weight of at least about 3000.

The foregoing discussion and the examples are intended as illustrativeof the present invention and are not to be taken as limiting. Stillother variations within the spirit and scope of the present inventionare possible and will readily present themselves to those skilled in theart.

1. A method for modulating glucose metabolism in a human patient whichcomprises orally administering to the patient, in an amount and at afrequency sufficient to maintain the patient's blood glucose level at apredetermined value, a composition comprising an insulinotropicallyeffective amount of isolated gurmarin and Sterculia urens exudate in arespective weight ratio in a range of about 1:50 to about 1:5.
 2. Themethod in accordance with claim 1 wherein the gurmarin and the exudateare administered in a weight ratio of gurmarin-to-exudate in the rangeof about 1:30 to about 1:10.
 3. The method in accordance with claim 1wherein the gurmarin and the exudate are administered in a weight ratioof gurmarin-to-exudate of about 1:25.